Diaphragm.



J. H. ELL-IS.

DIAPHRAGM.

APPLICATION mm AHLZB, 1911.

Patented Mar. 28,1916.

w/ v-zvssse sz UNITED I STATES PATENT OFFICE.

JAMES H. ELLIS, OF MILWAUKEE, WISCONSIN.

DIAPHRAGM.

Specification of Letters Patent. "Patented Mar. 28, 1916.

Application filed April 26, 1911. Serial No. 623,521. i

gree the property of responding accuratelyto its actuating influences, whether they be sound vibrations, in the case of a recorder, or surface undulations or variations, in the case of a reproducer.

I have found by experiment that a diaphragm excelling in its recording and reproducing properties may be made of celluloid without having the usual objection of diaphragms of other material, of producing false metallic tones or harsh and rasping tones, but which, on the other hand is capable of reproducing sound with all of its original value and expression, entirely free from false efi'ects.

Another object of this invention is to provide a diaphragm of anovel construction whereby cushioning gaskets of rubber or the like material may be entirely dispensed with,

thus avoiding the depreciation in efliciency of the instrument due to their deterioration. Another object of this invention is to so construct the diaphragm that it will Ivary in its flexibility from its periphery toward its center, with its greatest flexibility near its edge, whereby a greater area of vibration is secured.

With the above and other objects in view the invention consists in the diaphragm as herein claimed and all equivalents.

Referring to the accompanying drawings in which like characters of reference indicate the same parts in the different views:-

Figure 1 is a sectional view of a sound box 'for sound recording or reproducing machines with a diaphragm constructed in accordance with this invention; Fig. 2 is a top view of the diaphragm; Fig. 3 is a-bottom viewof the diaphragm; and, Fig.4; is a sectional view of the diaphragm showing a modified construction.

In these drawings 10. indicates a diaphragm comprising a thin sheet of celluloid. I have experimented with sheet celluloid of various thickness, but find that the thickness of approximately fifteen one thousandths of an inch is most suitable for the purpose. A celluloid diaphragm, whether possessing the features of construction herein disclosed or not, is found to possess the desirable characteristics above mentioned, and therefore I do not wish tobe limited to such particular construction except where specifically included in the claims.

In that form of the invention shown in Figs. 1, 2 and 3, the diskshaped celluloid sheet 10 is provided with a top ring 11 of celluloid and a bottom ring 12 of the same material preferably cemented thereto, and while both rings may be of the same external diameter as the diaphragm, one ring is of larger internal diameter than the other ring for the purpose of avoiding the formation of directly opposite clamping shoulders for the celluloid disk which would tend to have a shearing action thereonduring the vibrations of the disk that might be liable to cause the disk to be cut through at the inner edges of said rings. This advantage would be equally true of rings of other material, and consequently I do not desire to'be confined to the use of celluloid rings, except where specified in the claims, though such rings may be preferable because of their indestructible nature coupled with their resilint or cushioning .properties which enable he diaphragm to vibrate with greater faility than if the edges of the disk were held etween unyielding members.

It is not essential that the rings 11 and 12 be made separate from the disk portion, but they may be integral therewith, as shown central opening of the disk with its head upon the disk and its stem projecting below the disk where it is provided with an opening to receive a link l t-connecting it with the stylus lever 15, such anchor 13 being held firmly in place on the disk by cement. A modified form of anchor connection is flat headed anchor 13 is passed through a shown in Fig. 4 wherein a U-shaped staple 13 is employed with its ends bent outwardly and engaging the upper surface of the disk and its looped portion passing through a' central opening in the disk.

Another feature of novelty of the invention is a reinforcement 16 of the central portion of the disk, which is desirably of a cross the diaphragm will be at its peripheral portion, just-inside of its supporting edge, and its central portion will gradually" vary in flexibility, becoming less flexible as the center is approached. Such reinforcement maybe produced by the flexible cement holding the,

anchor 13 in place which may be celluloid cement or the like, but is preferably of collodion, or what is known on the market as New Skin. A reinforcement of this character is yielding and resilient and serves to stiffen the central portion of thediaphragm, or render it less flexible, so that minor influences affect the diaphragm to a greater degree and are not localized at its center.

By the use of celluloid for a diaphragm, the desired flexibility is provided together with that resiliency which is necessary to enable the diaphragm to recover after re sponding to one set of influences so as to more promptly and accurately respond to a succeeding set of influences. The nature of celluloid is such that it does not produce the metallic or rasping sound incident to vibrations of metallic diaphragms and diaphragms of mica and glass, and such materials. Celluloid may be readily produced of even gage throughout and without minute irregularities in its plane surface, as is usual with other materials, and which may account for foreign sounds in the reproduction, on the principle of the well known sharp sounding instrument. which produces a loud snapping noise upon bending a tongue of spring, metal which has an indentation embossed therein.

The gaskets of celluloid possess suflicient elasticity to enable the diaphragm'disk being The diaphragm may be molded and nrrnoas clamped between them to the desired degree which will not interfere with its vibrations,

but will prevent its chattering in its seat.

Such rings of celluloid furthermore are not subject to deterioration as with rubber and other rings now in use. The arrangement of the rings, whereby their inner edges are not opposite, avoids the possibility of their cutting through the disk as might otherwise be the case in. course of time.

The superior results obtained by the use of the diaphragm of this invention may be due to causes other than those specified, but the explanation given is that which I now believe to be correct.

What I claim as new and desire to secure by Letters Patent is:

1. A diaphragm for sound recording or reproducing instruments, comprising a flexible disk, and a resilient plastic reinforcement for the center thereof in. the shape of a cross with its members tapering in width from the center toward their outer ends and diminishing in thickness from the center toward their outer ends.

2. A diaphragm for sound recording or reproducing instruments, comprising a flexible disk, a resilient plastic reinforcement at the center thereof comprising an application of cement in the'shape of a star with its points tapering in width and diminishing v in thickness toward their outer ends and ter mina'ting before reaching the edge of the disk.

3. A diaphragm for sound recording or reproducing instruments, comprising a flexible disk, a resilient plasticreinforcement at the center thereof comprising an application of cement of a star shape with its points tapering in width and diminishing in thickness toward their outer ends, and a headed anchor passing through the center of the disk arid held in place by the cement reinforcement to form a stylus connection.

4. A diaphragm for sound'recording or reproducing instruments, comprising a disk .of sheet celluloid, and a resilient plasticreinforcement at the center thereof comprising an application of flexible cement, as collodion of a star shape, increasing in thickness toward the center thereof.

In testimony whereof I aflix my signature, in presence of two witnesses.

I JAMES H. ELLIS.

Witnesses:

R. S. C. CALDWELL, KATHERINE Horn. 

